Question

我需要听大约40个订阅（在接下来的几天里这个数量会增加）。

如果只有一个订阅，那么我将完成以下操作，

const subName = 'mysubscription'
const pubSubClient = new PubSub()
const startVidsubscription = pubSubClient.subscription(subName)
startVidsubscription.on('message', messageHandler)

const messageHandler = async(message) => {
// do stuff

}

但是，当我有数十个订阅时，我无法执行此操作。因此，我正在尝试以下操作：

// the name is the name of each subscription and the variable is the variable name in which I will be holding the subscription object. 
var subscriptionDetails = [
    {'name': 'M10057-sub-cam1Api', 'variable': 'M10057Subscription'},
    {'name': 'M10058-sub-cam1Api', 'variable': 'M10058Subscription'},
    {'name': 'M10059-sub-cam1Api', 'variable': 'M10059Subscription'},
]

for(const subscription of subscriptionDetails){
        var subscription.variable = pubSubClient.subscription(subscription.name)
        subscription.variable.on('message', messageHandler)
    }

但这给了我类似Unexpected token, expected ;的错误。

任何人都请让我知道在Node.js中收听大量订阅的推荐方法

Answer 1

您的一般方法应该可行。将订阅对象分配给已经定义为字符串的subscription.variable可能会遇到问题。

类似以下的方法将起作用：

const {PubSub} = require('@google-cloud/pubsub');

const pubSubClient = new PubSub();
const messageHandler = async(message) => {
  // ... handle message ...
};

var subscriptionDetails = [
  {'name': 'M10057-sub-cam1Api'},
  {'name': 'M10058-sub-cam1Api'},
  {'name': 'M10059-sub-cam1Api'},
];

for (const subscription of subscriptionDetails) {
  subscription.variable = pubSubClient.subscription(subscription.name);
  subscription.variable.on('message', messageHandler);
}

然后您可以使用variable中的subscriptionDetails字段来引用订阅对象。

如果要引用名称为“ M10057Subscription”的订阅对象，则可以创建订阅对象的映射：

var subscriptionDetails = [
  {'name': 'M10057-sub-cam1Api', 'variable': 'M10057Subscription'},
  {'name': 'M10058-sub-cam1Api', 'variable': 'M10058Subscription'},
  {'name': 'M10059-sub-cam1Api', 'variable': 'M10059Subscription'},
];

var subscriptionObjects = {};

for (const subscription of subscriptionDetails) {
  subscriptionObjects[subscription.variable] = pubSubClient.subscription(subscription.name);
  subscriptionObjects[subscription.variable].on('message', messageHandler);
}

// subscriptionObjects['M10057Subscription'] is a subscription object

在nodejs中创建大量Google pubsub订阅者的推荐方法是什么？

1 个答案: